This invention relates to a spray nozzle for intermittently or cyclically spraying a material using a propellant fluid such as compressed air which prevents dripping between cycles. More particularly, this invention relates to the intermittent and drip-free spraying of lubricant. A particularly useful application is the distribution of lubricant to the wheels of vehicles which run on rails or tracks.
When a wheel rolls on a track it has rolling contact with the track and theoretically does not require lubrication. Yet, it is found that applying a very slight amount of lubricant therebetween contributes to a smoother and quieter ride. This is particularly effective when applied on curves to reduce rubbing which takes place between the flanges of the outer wheels and the outer rail due to centrifugal force.
It is known to provide an automatic acting system whereby lubricant can be sprayed to the flanges or tires of wheels such as rail cars, when same are running around curves. Such a system is disclosed in U.S. Pat. No. 2,567,774.
However, it is important, since rail cars cross over roadways, to minimize or eliminate unwanted drippage of lubricating oil during periods in between spraying cycles. Avoidance of drippage also assists in conservation of the lubricant and the attendant cost reduction.